The purpose of the proposed research program is to quantify the contribution of small eye movements to vision. The effect of eye movements is assessed with stabilized images, achieved by eliminating the normal movements of the retinal image that result from eye movements. Vision is then studied under the temporally and spatially steady conditions supplied by such a stabilized image. In this proposal, a gain mechanism which adjusts local sensitivity to a temporal and space average level is proposed as the basis for the gradual disappearance of the stabilized image. A critical indication of the gain control process is the apparent phase reversed (APR) image. APR refers to the appearance of the faded stabilized image, in negative phase, upon a step increase in the average luminance of the target. It implies the presence of a mulitplicative nonlinearity. In the proposed research, APR and the two other indications of the gain process, the fading of a stabilized image and the after image, will be studied with uniform increment, contrast matching, and local increment techniques under various spatio-temporal and luminance conditions. In this way, the operating range and the nature of the gain control mechanism (whether it is multiplicative, subtractive, or a combination of both) will be determined. A major thrust of the research effort is to determine the connection of stabilized fading and local adaptation, and to develop a model that accounts for not only phenomena associated with stabilized viewing, but also some aspects of normal light adaptation. Eye movements are simulated to demonstrate quantitatively that one model accounts for both stabilized and normal vision.